I have asked this question 3 times. Can someone please answer this time?

So I always see, especially when talking about terrain parks, people saying that they want to or have done a 3 or a 5 or a 7 off a ski jump or cliff. I also see some people saying they wish the jumps were big enough to do a 5 or a 7. What do the numbers mean? Thank you and I will give the best answer 10 points. Also I'm not sure if maybe this is a snowboarder term or if it is both skiers and boarders or a skier term.